Chromium poisoning and degradation at Gd0.2Ce0.8O2-impregnated LaNi0.6Fe0.4O3-δ cathode for solid oxide fuel cell

The degradation of cathode performances by chromium poisoning is studied at two cathodes LaNi0.6Fe0.4O3-delta (LNF) and 21.3 wt.% Gd0.2Ce0.8O2 (GDC)-impregnated LaNi0.6Fe0.4O3-delta on the scandia stabilized zirconia (ScSZ) electrolyte. Specific polarization resistance (R-p) increases with time to the power of 1/3 and 1/5 in LNF and 21.3 wt.% GDC-impregnated LNF cathode after operating under a cathodic current density of 50 mA cm(-2) under exposure of Cr vapors at 750 degrees C for 370 h and 1042 h, respectively. electrochemical impedance spectroscopy (EIS) illustrate that LNF exhibits far greater R-p than that of 21.3 wt.%GDC-impregnated LNF under exposure of Cr vapors due to strong Cr deposition at LNF/ScSZ interface. No significant degradation in performance has been observed after 1042 h of operating under a cathodic current density of 50 mA cm(-2) under exposure of Cr vapors at 750 degrees C due to very little Cr deposition at 21.3 wt.%GDC-impregnated LNF/ScSZ interface, suggesting little poisoning effect for O-2 reduction on 21.3 wt.%GDC-impregnated LNF cathode. The results demonstrate that 21.3 wt.%GDC-impregnated LNF cathode has a high resistance toward Cr deposition and high tolerance toward Cr poisoning. (C) 2012 Elsevier By. All rights reserved.